The objective of this proposal is to improve radiographic methods for assessing total hip-joint replacements with regard to socket wear, including associated magnification factors, component orientation and acrylic cement failure. This will be achieved using laboratory studies to simulate the necessary parameters analyzed in the companion clinical studies. These methods will illustrate the limitations in such procedures and provide the essential framework for improved clinical techniques of known accuracy. A rotating patient-support system will be developed to provide the required consistency to the various studies and simplify the radiographer's task of standardizing the patient's orientation. The radiographic calibrations will be used to assess the wear rates of the Trapezoidal-28 hip replacement for comparison with both the Charnley design and the data from friction and wear studies of new materials. This wear data will also be used as the basis for radiographic studies of the surface-replacement hip-joint designs. The developed orientation studies will determine whether there is an optimal position for the hip-joint components with respect to impaction, subluxation and dislocation problems in patients. These data will aid both patients' evaluations with modified hip proformas, as well as methods for positioning at surgery. The acrylic studies will demonstrate the magnitude and type of cracks which can be visualized radiographically and the optimal clinical procedure for use in the patient-support system. These data will be used in the improved analysis of joint failure modes.